The polymer raw material film, neatly stacked in rolls like silver silk, undergoes multiple processes such as pretreatment, multiple biaxial stretching, and heat setting to transform into a thin lithium battery separator like a cicada's wing. This is a scene that the reporter recently saw on the Yuxi Enjie 5 μ m (micrometer) lithium battery separator production line under Yunnan Enjie New Materials Co., Ltd. (hereinafter referred to as "Enjie Co., Ltd."). The world's most advanced lithium battery separator production line, which was recently put into operation, has produced 5 μ m ultra-thin and high-strength lithium battery separator products through polymer material technology developed by Enjie Corporation, promoting new development in the lithium battery industry. The lithium battery separator is a thin film between the positive and negative electrodes of a lithium battery, with a thickness of only one tenth of a human hair. Its cost accounts for about 10% of the cost of a lithium battery and is one of the core components of a lithium battery. Through professional equipment magnification observation, it can be seen that the surfaces of these films are covered with nano-sized black gray flocculent micropores. It is the presence of these micropores that allows lithium ions to pass smoothly, forming a charging and discharging circuit, ensuring the normal operation of lithium batteries. The diaphragm has two main functions: to isolate the positive and negative electrodes and to provide a channel for lithium ion transport. ”Pang Qizhi, Investment Director of Enjie Co., Ltd., said that the research and development of separators is difficult, with deep technical content and high added value, making them the lithium battery material with the highest investment intensity. Before 2010, lithium battery separator technology was monopolized by countries such as the United States and Japan, and China was at the mercy of others in this field. ”Pang Qizhi introduced that after years of difficult research and development, Enjie Group has completely broken the monopoly of wet process lithium battery separator technology by foreign enterprises, and has become the industry leader with the highest market share in the world for several consecutive years. Only continuous technological innovation can ensure a leading position. ”Pang Qizhi said that the separator plays a decisive role in the safety, energy density, and cycle life of lithium batteries. "The 5 μ m ultra-thin high-strength platform product is the result of our continuous breakthroughs in industry technology bottlenecks. In the field of lithium battery separators, thickness, strength, and ion permeability cannot be achieved simultaneously. ”Cheng Xu, the head of the landing department of Enjie Global Product Development Center, introduced that the traditional concept holds that the thinner the diaphragm, the lower the strength. The 5 μ m separator developed by Enjie Corporation achieves a balance between thickness, strength, and ion permeability, completely breaking the industry's long-standing understanding and improving the performance boundary of lithium battery separators. Cheng Xu said that in terms of material selection, the R&D team used high-performance polymer materials and carried out special modification treatments to enhance the intermolecular forces and improve the strength of the membrane; In the production process, precise control of process parameters such as temperature, pressure, and stretching rate has been achieved to precisely regulate the microstructure of the diaphragm and improve ion permeability. The comprehensive innovation from materials to processes has increased the needle punching strength of 5 μ m membranes by 16.7% compared to 7 μ m membranes, and reduced the internal resistance of membranes by 20.9%. Industry evaluation shows that 5 μ m separators can significantly improve the energy density of power batteries, enhance charging efficiency, and reduce the risk of thermal runaway of battery cells, injecting new impetus into the development of the power battery industry. At present, 5 μ m ultra-thin high-strength products have been recognized by multiple customers and are expected to be widely promoted and applied in the power battery industry in the future. ”Pang Qizhi said that this also indicates that technological innovation is the main way to break the "involution" competition. We will consolidate our industry position in the field of lithium battery separators through continuous research and development innovation. At the same time, based on our technological accumulation and continuous deep cultivation in the field of polymer materials, we will actively layout in the field of solid electrolytes. ”Pang Qizhi stated. At present, Enjie Group's semi-solid electrolyte membrane has achieved preliminary commercialization, with two production lines capable of mass production and supply of semi-solid battery separators. Meanwhile, the 10 ton pilot line project for sulfide solid electrolyte materials has been fully completed recently, mastering the key technologies of the entire chain from core raw materials to electrolyte membranes. We will expand relevant production capacity construction according to market demand, and achieve the 'three-level leap' development goal of research and development, pilot testing, and mass production, "said Pang Qizhi. (New Society)